低温核反应堆采用了一体化布置、自稳压、全功率范围自然循环、非能动余热排出等一系列先进的设计概念和技术，具有固有安全性好、结构紧凑、环境影响小等突出优点。除了在核能供热、核能海水淡化等领域有广泛的应用前景外，由低温堆构成的小型灵活的核电站，可有效地解决一些特殊领域的电力需要，在某些特定的应用场合有重要的应用价值。 如何对低温堆核电站的运行功率进行有效的控制，满足在大的功率变化范围内良好的控制特性要求，有许多技术问题尚待解决，需要通过建模仿真研究才能解决。本文开展的建模工作和动态特性研究，为控制系统及控制特性的仿真研究提供低温堆核电站的动态数学模型，是建模仿真研究工作的重要组成部分，具有重要的理论价值和实用价值。 论文开展的研究工作及取得的主要成果如下： (1)针对低温堆核电站的特点，运用机理建模法建立了一个满足大功率范围内控制特性仿真要求的非线性、集总参数的动态数学模型，该模型包括自然循环的反应堆堆芯、一回路、主换热器的热工水力和传热过程，以及中子动力学过程。 (2)利用所建立的动态模型在Matlab的Simulink环境下进行了低温核电站动态特性的数字仿真，结果表明：所建立的模型能够在大功率范围内正确反映低温堆核电站的主要动态特性，可用于低温堆核电站控制系统的分析、设计，以及控制特性的仿真研究。 (3)根据对系统稳态特性的分析，给出了二种可行的稳态运行方案：一是堆芯出口温度恒定的稳态运行方案；二是在高功率段堆芯出口温度恒定，在低功率段堆芯出口温度线性变化的稳态运行方案。前者保持了上气室温度恒定，有利于一回路参数的稳定；而后者则兼顾了一回路和中间回路的特定和要求。

For Low-Temperature-Reactor (LTR), the integrative disposition is adopted; The primary coolant flow is working on the bases of natural circulation within the entire power range; The pressure is self-maintaining in the vessel. So LTR has the advantages because of the intrinsic safety feature, the compact structure, the little pollution and economy cost. Besides the widely use of nuclear heating reactor and nuclear desalt project， LTR can be also used in the pint-sized nuclear power plant and shows its important value in some special place. This dissertation focuses on the LTR Nuclear Power Plant (NPP). In order to let LTR NPP run under the special mode under which the reactor power can be regulated to meet the power gird load and aim to reach the control objective that can regulate the reactor power to meet the load in large power range within little time, we establish the dynamic mathematical model which is different to pressurized-water reactor NPP and nuclear heating reactor. The main results of this dissertation are as follows: (a)In accordance with the characteristics of LTR NPP, studying on the thermal and hydraulic theory, using theory analysis method, a simple dynamic mathematical model suitable for control system simulation is developed. This model includes reactor core, the primary loop, natural circulation, reactive and point neutrons kinetic formula and primary heating exchanger. In the process of establishing the model, it is considered adequately that this model is used for the control system simulation that is in large power range. For example, in the process of establishing the reactor core and primary heating exchanger, the coolant’s materials properties cannot be used as constants, but be calculated by a special function. (b)The established model simulation is base on the Matlab/Simulink platform. Studying on the results, the elementary qualitative validation of the model can be made. These data are useful for the design of control scheme. (c)Two feasible steady-state programs are attained according to the main characteristics of the LTR. One is the constant-outlet-temperature program. And the other is the lower-outlet-temperature in lower power range. The former one keeps the temperature of upper gas room constant. So it is useful for the stability of the primary loop’s parameters. And the latter one also considers the design of the mid-loop.